The invention concerns a device for the multi-sided coating of workpieces, in particular panel-like furniture parts, by means of a feeder system comprising a base plate having a plurality of lifting bolts distributed over the base plate in a grid-like manner and which can be adjusted vertically vis-a-vis the base plate between a retracted rest position and an extended coating position, wherein actuating means are provided for the vertical adjustment of the lifting bolts and locking means to lock the individual lifting bolts in the desired vertical position.
Devices of this type are used for furniture parts in which not only the front but also the surrounding side edge surfaces are to be coated with a veneer, a foil material or the like, whereby this coating takes place by heat and pressure in a pressing device. In particular, the workpieces must be lifted by the lifting bolts vis-a-vis the pallet placed on the base plate and supporting said workpieces to enable a trouble-free coating of the edge surfaces. In this case, it is important that only those lifting bolts be raised into the extended coating position which are completely covered by the workpiece while the lifting bolts which are not covered or not completely covered should remain in the rest position in order not to impair the coating process of the edge surfaces.
In the prior art, there are already many descriptions of a feeder system of this type and also the described difficulties, namely to raise and/or not to lower only those lifting bolts which do not impair the coating process of the edge surfaces. In this connection, by way of example, reference is made to EP 0 978 707 from which it is already known, based on all of lifting bolts raised into the coating position, to lock those lifting bolts in the coating position by means of pawls which are completely covered by the workpiece, while the remaining lifting bolts are lowered into the lower rest position by separate adjusting elements. Ultimately, the adjusting elements can be jointly raised or lowered by driving a board carrying the adjusting elements; however, in order to be able to transmit the desired lift position to the lifting bolts, the adjusting elements must first be brought into the lower or upper position by means of separate actuating means for each lifting bolt, depending on the position into which the lifting bolt allocated to the respective adjusting element is to come to lie.
Thus, the known feeder system has its own locking means and also its own actuating means for each lifting bolt, whereby, for further simplification, all actuating means can be driven by a common lifting mechanism.
Based on the foregoing, the object of the invention is to provide a device of the aforementioned type which enables both the raising or lowering and locking of the lifting bolts in a simplified manner and to thus reduce the operative expenditure of a feeder system. According to the invention, this object is solved therein that the lifting bolts distributed in a grid-like manner are arranged in rows and lines in such a way that each lifting bolt is allocated to a row and a line in each case and that actuating means which can be separately activated and act on all lifting bolts of the line are allocated to each line and that locking means which can be separately activated and act on all lifting bolts of the row are allocated to each row.
This results in the advantage that the device of the invention makes do with one actuating means each per line and one locking means per row and is, nevertheless, able to feed workpieces in such a way that they are only carried by lifting bolts which are completely covered, whereas the lifting bolts not covered or not completely covered remain in the downward driven rest position. It is not necessary to individually actuate every lifting bolt and to provide it with separate actuating and locking means.
In the present invention, the arrangement of the lifting bolts in lines or rows is understood to be a division of the lifting bolt grid into individual groups and the joint actuating of these groups in such a way that each lifting bolt can be locked or released by affiliation with a group and be actuated by simultaneous affiliation with a group and consequently raised or lowered. A simple and clear special case lies therein to dispose every lifting bolt so as to be aligned with the other lifting bolts of its row or its line, whereby the rows and the lines are directed at a right angle to one another. However, other divisions and arrangements of the groups or lifting bolts are also possible. Thus, the rows or columns can also, for example, extend in a zigzag manner, be directed at a specific angle to one another, etc. The expressions xe2x80x9crowxe2x80x9d or xe2x80x9ccolumnxe2x80x9d also do not signify any definition with respect to the pattern, shape or direction of the respective group.
While the actuating means advantageously operate pneumatically and as a result enable a problem-free parallel connection of all lifting bolts provided in a line, with respect to the locking means, it is practical if these act mechanically on the lifting means and lock them in the desired vertical position, whereby this locking is usefully accomplished by a blocking element which is positively locked with the lifting bolts. For example, a horizontal bar which travels between a locked position and a release position is suitable as blocking element which acts on all lifting bolts of the same row. A bar of this type can, for example, have keyhole-shaped elongated slots for the respective lifting bolts, so that the aperture range defines the release a way that they are only carried by lifting bolts which are completely covered, whereas the lifting bolts not covered or not completely covered remain in the downward driven rest position. It is not necessary to individually actuate every lifting bolt and to provide it with separate actuating and locking means.
In the present invention, the arrangement of the lifting bolts in lines or rows is understood to be a division of the lifting bolt grid into individual groups and the joint actuating of these groups in such a way that each lifting bolt can be locked or released by affiliation with a group and be actuated by simultaneous affiliation with a group and consequently raised or lowered. A simple and clear special case lies therein to dispose every lifting bolt so as to be aligned with the other lifting bolts of its row or its line, whereby the rows and the lines are directed at a right angle to one another. However, other divisions and arrangements of the groups or lifting bolts are also possible. Thus, the rows or columns can also, for example, extend in a zigzag manner, be directed at a specific angle to one another, etc. The expressions xe2x80x9crowxe2x80x9d or xe2x80x9ccolumnxe2x80x9d also do not signify any definition with respect to the pattern, shape or direction of the respective group.
While the actuating means advantageously operate pneumatically and as a result enable a problem-free parallel connection of all lifting bolts provided in a line, with respect to the locking means, it is advantageous if these act mechanically on the lifting means and lock them in the desired vertical position, whereby this locking is usefully accomplished by a blocking element which is positively locked with the lifting bolts. For example, a horizontal bar which travels between a locked position and a release position is suitable as blocking element which acts on all lifting bolts of the same row. A bar of this type can, for example, have keyhole-shaped elongated slots for the respective lifting bolts, so that the aperture range defines the release position with a larger cross section and thus enables a vertical travel of the lifting bolt, while the aperture section with the smaller cross section is used for the positive locking with a corresponding section of the lifting bolt, in order to thus prevent its vertical movement.
The actuation by line and the locking by rows of the lifting bolts according to the invention can be adjusted to one another in such a way that, in the described device, the lifting bolts of a line are each actuated together and the lifting bolts of a row are each locked together. As already noted above, the coating process of the workpieces should not be impaired by the top of bolts protruding laterally vis-a-vis the workpiece; in this case, it is essential that only the lifting bolts completely covered by the workpiece carry the workpiece in the coating position.
Thus, according to the invention, it is provided that the lifting bolts of that row in the rest position are locked in which lifting bolts not covered or not completely covered are found and that, subsequently, the lifting bolts not locked of only those lines are raised from the rest position into the coating position in which these lifting bolts not locked are completely covered by the workpiece. Thus, first of all, the rows of lifting bolts not required are locked, so that the subsequent pneumatic actuation of the required lines of lifting bolts only result in raising those lifting bolts which are not locked. The lifting bolts already locked and then acted upon pneumatically remain in the lower rest position, so that the pneumatic actuation does not ultimately effect the entire lines of lifting bolts but only those lifting bolts of the lines which have not been locked. It can be easily seen that workpieces with various shapes can be stored or coated with this simple procedure.
To finish workpieces that have complex: shapes or workpieces that are to be combined to form a complicated laying pattern, it is advisable to raise the lifting bolts one after the other, row after row. In this case, the lifting bolts of only those lines are actuated for each row in which a lifting bolt to be raised is found in this row and subsequently all lifting bolts of this row are locked in their respective rest position. Moreover, it is advisable that, prior to raising the lifting bolts of a row, to only release the lifting bolts of this row, while the lifting bolts of the other rows remain locked in their respective rest position. This process is continued row after row until all lifting bolts to be raised and which are covered after the workpiece has been placed on them are found in the coating position.
If it is ascertained that the workpieces are positioned in such a way that a number of rows are, simultaneously covered, then the lifting bolts of several rows can be simultaneously released, raised and locked together as the lifting bolts to be raised and arranged in the same row, which means a saving of time when vertically positioning the lifting bolts.
With this method, it does not make any difference whether the workpieces are placed on the lifting bolts before or after the lifting bolts have been raised into the coating position, since neither the actuating or the locking process are dependent on or impaired by a workpiece which has been placed thereon. Admittedly, the second variant of positioning it subsequently offers a substantial advantage therein that the workpiece is only subjected to uniform movements after being placed on it and prior to the coating, without this resulting, in tilting, tipping, etc. On the contrary, when the lifting bolts on which the workpieces have already been placed are raised row by row, the workpiece is not raised parallel, i.e. always in a horizontal position, but successively, i.e. first brought into an inclined position starting at an edge by the lifting bolts there and only then placed into the desired horizontal coating position after almost all lifting bolts have been raised. This can result in uncontrollable tilting motions and, in some circumstances, even to changes in its position.
The preferred procedure is contrary to a part of the prior art in which only the positioned workpiece results therein that lifting bolts which cannot be used travel downward into the rest position. For this purpose, either sensors or pneumatic line sections open in direction of the top of the lifting bolts are provided on the lifting bolts, said line sections identifying the lifting bolts that are not required and triggering their lowering.
According to the present invention, the lifting bolts not required are identified thereby that the workpiece is recorded with respect to its shape, dimensions and position prior to actuating or locking the lifting bolts, for which purpose a scanner is provided which produces a workpiece information about the workpiece data and that the actuating means and the locking means can be activated taking the workpiece information into consideration. It is easiest if the scanner scans the workpiece optically which can, for example, be done laterally, outside of the press prior to the workpiece being conveyed into the press, while the feeder system is preferably situated in the press but it can also be integrated in the pallet.
If a control mechanism is connected to the actuating means and locking means which controls the actuating means and locking means in dependency on the workpiece information, then the raising and lowering of the lifting bolts can actually be obtained in dependency on the shape of the workpiece, even if the workpiece has not as yet been placed on the lifting bolts. For this purpose, the control mechanism only activates those actuating means in whose line at least one lifting bolt is found which is completely covered by a workpiece subsequently placed on it, whereby, prior to activating the actuating means, the control mechanism only steers the locking means in the sense of locking the lifting bolts in whose row lifting bolts are found which are incompletely covered or nor covered by the workpiece.
Instead of using a scanning device to take the workpiece data into account, it is also possible that the control mechanism gives a specific positioning pattern to be adapted to the workpiece to be coated from an optimization program and actuates the lifting bolts or their actuating and locking means according to this positioning pattern. Workpieces can then be placed on the raised lifting bolts either automatically or by an attendant. This procedure is recommended especially for large series, whereby the lifting bolts can also advantageously remain in their respective vertical position for several coating cycles with constant positioning pattern. As a result, the cycle frequency of the coating processes can be increased and the wear and tear on the feeder system reduced.
Moreover, according to the present invention, an overall procedural sequence proposed for processing workpieces, in particular for handling panel-like furniture parts to be coated, which comprises the following procedural steps:
a) scanning the workpiece to be finished with respect to its shape and/or dimensions,
b) producing a workpiece information from the scanned data,
c) steering a feeder system having a plurality of grid-like lifting bolts arranged in rows and lines and used to position workpieces before and/or after their processing with aid of workpiece information in such a way that the lifting bolts completely covered by the workpieces after they have been placed on them are raised by rows by actuating means each acting on all lifting bolts of a line from their lower rest position into their upper coating position,
c1) whereby the actuating means of those lines are activated for each row in which a lifting bolt to be raised and found in this row is located and
c2) whereby all lifting bolts of this row are subsequently locked in their respective vertical position by common locking means, and
c3) whereby procedural step c1) and then procedural step c2) are carried out successively for all further rows in which a lifting bolt to be raised is found,
d) placing the workpiece onto the raised lifting bolt and
e) coating the workpiece, in particular of the panel-like furniture part.
This sequence is advantageously supplemented thereby that, prior to carrying out procedural step c1) for a row of lifting bolts, only this row is released by the associated common locking means, while the lifting bolts of the remaining rows remain locked by their locking means. In this case, the lifting bolts are only advantageously released or actuated by rows when at least one lifting bolt of this row is completely covered by the workpiece and must be raised. The actuation by lines of the lifting bolts is also carried out when at least one lifting bolt is completely covered by the workpiece. In this case, the other lifting bolts are in rows which have been locked, as a result of which the actuation does not impair these locked lifting bolts.